With the rapid development of flat panel display technologies, the organic light-emitting display (OLED) has become more and more popular due to its excellent characteristics such as self-luminescence, high brightness, a wide viewing angle, and fast response.
The light-emitting devices used in current OLED display panels basically adopt a stacked structure. For the light-emitting device, a basic structure is formed by an anode, an organic functional layer, and a cathode. The organic functional layer includes a light-emitting layer and other light-emitting auxiliary layers. On the light-emitting layer, electrons and holes are combined to generate excitons which are unstable and thus release energy. The energy is transferred to the molecules of the organic light-emitting substance in the light-emitting layer, causing their transition from a ground state to an excited state. Since the excited state is very unstable, the excited molecules return from the excited state to the ground state, and light is generated due to the radiation transition. Main functions of other light-emitting auxiliary layers include injecting and transmitting electrons and holes, thereby improving the luminous efficiency of the light-emitting layer. Based on properties and service life of current light-emitting materials, the luminous efficiency and service life of OLED light-emitting devices have become a very important practical topic in the field of OLED display.